Hi! Someone on Twitter pointed me here since I'm out of ideas of what to do to get my MDP-650 working again.

It used to work like a charm, but after about 2 months of not using it the following happens when I put in a LD:

The disc gets raised

The disc gets lowered (this is how it always goes, so nothing unusual here yet)

I press play

The disc gets raised again

The laser module moves back and forth around 4 times, with about 1 second between each try

The disc gets lowered again, the player just displays "disc"

Same when I try to play a CD, except the player displays "no disc" then. The player has an infrared led and photo diode pointing up at the LD, so that's why the player knows there's a LD in there even when it can't read it.

What I tried so far:

Lubing the moving parts, though that was not be suspected to be the problem to begin with

Moving the LD spindle manually. It started spinning by itself eventually and the player was apparently trying to play, but it only spun for about 2 seconds, then the player lowered the disc again after the LD stopped spinning.

Cleaned both laser diodes

So.. I'm out of ideas. I assume the disc should start spinning before the laser makes any attempt reading it? I just can't figure out what prevents the disc from spinning up.

I didn't notice anything off with the picture before it broke. Not being a top-notch Pioneer unit the picture quality was never amazing, but I never had any problems with the player (apart from the belt I had to replace right after I bought it)

[edit] I also mailed the service manual to the specified address by the way as I noticed it wasn't in the directory.

I don't think there's a belt, the way (I think) it works is that the optical assembly is mounted on a hinge, on one side there's a gear with some kind of ramp that controls the tilt of the whole assembly. I don't think the laser can raise otherwise.

Here you can see where the skew motor is located

More detailed schematic

Problem is, I absolutely can't see if the skew motor is doing anything when the drawer is inside. :/

on that 2-5 page where it shows the part attached to the spindle it says 33mm check that one out.if its not correct then your disc will be too high or too low for the laser.

everything has to be perfect.I sort of remember that from something else I fixed in the past non LD related, can't remember what it was but that was the issue some shifting on the spindle shaft.good luck

I'll try asap if the skew motor does anything. The player has a sensor to detect if a Laserdisc is inside, so if I put something reflective there I should be able to trick the player into trying to play.

Also, I've been to a repair shop today of some old guy who is really into repairing old hardware. In his opinion the laser assembly is broken as neither of the 2 lasers turn on when the player is trying to read the disc. That was with a CD inside, so I assume the player would only try the CD laser then, but not the LD laser.

So.. is the LD laser actually visible? I could try to fool the player into thinking an LD is inserted and try to see if the laser does anything. (I'm always extremely careful with lasers, but I'll just keep lots of distance)

make sure that platter that is connected to the spindle is at the correct height.too low and the laser won't read, too high and it won't read.

that skew motor looks like it will move the laser, that may not be the issue, that platter to hold up the CD/LD may have slid down and no amount of other tweeking will fix an issue that is from another moved part.

make sure that set screw is tight, and also double check to make sure its 33mm, it could have moved 1mm and you are SOL.

When I first had my CLD-1450 player and was modding it for NTSC playback I took the time and cleaned the various surfaces. As a part of this I cleaned (or so I thought) the laser lens but after doing so the player wouldn't play. It did exactly what you are saying as in it would load the disc, lift the disc onto the motor, the laser would search about a bit then it would set the disc back down.

At first I thought I've made a balls here and knocked / misaligned something. Spent hours taking the player to bits and carefully reassembled it to no effect.

Not that I could see it but turns out as I was cleaning it initally I must of picked up something and rubbed it onto the laser lens. Silly thing to do but it stopped the player from reading. After giving the lens a good going over with some cotton buds it played first time. I know you say you have tried cleaning it but I would recommend giving it one more go, just incase.

So.. the skew motor does work, I managed to peek in while a Laserdisc was loaded. The Player only seems to use the skew motor when a Laserdisc is loaded, as the CD laser can raise itself but the LD laser seemingly can't.I noticed that the skew gear was all the way in the "high" position, so I manually turned the gear so it'd be at the other end. And voila, a CD was played! I repeated the same thing, turning the gear all the way back and it not only recognized the Laserdisc, but also started playing (for a few seconds that is, but it's a start).

This leads me to the assumption that the discs are simply not at the right distance to the laser, as rein-o suggested, I'll see what I can do about that

Aww yiss! My LD player is playing Laserdiscs (and CDs) again! Well, I didn't try on the TV yet but I assume I'm also getting an image

All I did was playing around with the height adjustment screw of the spindle, thanks so much for the tip rein-o! It was impossible to accurately measure the distance, but at least I got a rough idea. Probably not at the perfect height, but it seems that the whole thing just slipped down over the years.

Here's where I adjusted the height.

Now there's another (small) issue. Then I press stop on the player the player first stops spinning the motor, then I hear some active braking, but that only lasts for about 2 seconds, then the disc is still spinning and it takes about 15 seconds until the disc fully stops and I can do anything. In the past the player managed to stop the disc within maybe 3-4 seconds.Does anyone know how the mechanism to stop the disc works? is there some kind of brake?

Anyway, thanks so much for all your help, I'm really happy that it works again!

no problem, grasshopper fixed a CD player of mine once and gave me the service manual, that was the bulletin that was posted.

your other issue sounds like the thin rubber pad/ring on that black platter is slipping.you can search up here on the forum, you can try cleaning it or replace it, don't know the size and you may be able to get away withthe pioneer rubber ring but I think its around 25 or 30 bucks for the part, but that's just a guess.

personally I would only worry when it messes up with start up of the disc not with stopping, and it may cause label wear.good luck.

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